Polio surveillance in Lao PDR: a two-year experience of active case search, 1994-96

The underdeveloped health infrastructure and limited epidemiological data on polio are major obstacles to the establishment of the acute flaccid paralysis (AFP) surveillance system in Lao People's Democratic Republic (Lao PDR). We initiated a nationwide active case search for case investigations at the community level in March 1994 to support the development of the AFP surveillance system. We identified 164 polio cases that occurred between 1979 and 1993 in 511 villages, indicating that wild poliovirus had circulated extensively during that period. Of these, only 59 (36 per cent) had visited health facilities, and polio was diagnosed in 15 (9 per cent). As national immunization days (NIDs) progressed, the number of polio cases decreased to an undetectable level after 1994. The active case search was useful for educating the local staff about AFP and the components of a surveillance system, and as an adjunct to national AFP surveillance programme in the country as it approaches the goal of polio eradication.